johannesburg was the golden city. >> reporter: but johannesburg in the 1940s isn't albright lights and big opportunities. particularly for a young black man. >> here was this strapping young man who had been part of this royal village who felt this high sense of self-esteem, and he was treated like dirt, like all of the other africans were. >> reporter: here in joe nan hessburg under the harsh realities of racism, mandela meets a man who will change his life forever. >> he walked into walter's office. he was a real estate agent. and mandela was astonished. he realized there was another life that was available. >> reporter: he was also an active member of the african national congress. started in 1912, the anc was created to peacefully advocate for political rights for south africa's blacks. mandela sees the future of the organization. >> he said we at the anc wanted to be a mass organization, and we needed a mass leader. and wen thun day nelson mandela walked into his office. he realized that's the guy. >> reporter: he becomes mandela's mentor and encourages him to earn a law degree. h